In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters. In any of these forms, fatty acids are both important dietary sources of fuel for animals and important structural components for cells.
In organic chemistry, a ketone is a functional group with the structure R−C(=O)−R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group −C(=O)−. The simplest ketone is acetone, with the formula (CH3)2CO. Many ketones are of great importance in biology and in industry. Examples include many sugars (ketoses), many steroids, and the solvent acetone.
A triglyceride is an ester derived from glycerol and three fatty acids. Triglycerides are the main constituents of body fat in humans and other vertebrates, as well as vegetable fat. They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, and are a major component of human skin oils.
Pyruvic acid (IUPAC name: 2-oxopropanoic acid, also called acetoic acid) (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell.
Stearic acid is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a waxy solid with the formula CH3(CH2)16CO2H. Its name comes from the Greek word στέαρ "stéar", which means tallow. The salts and esters of stearic acid are called stearates. As its ester, stearic acid is one of the most common saturated fatty acids found in nature following palmitic acid. The triglyceride derived from three molecules of stearic acid is called stearin.
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and MnO−
4, an intensely pink to purple solution.
Fatty acid metabolism consists of various metabolic processes involving or closely related to fatty acids, a family of molecules classified within the lipid macronutrient category. These processes can mainly be divided into (1) catabolic processes that generate energy and (2) anabolic processes where they serve as building blocks for other compounds.
In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport chain. It is named as such because the beta carbon of the fatty acid undergoes oxidation to a carbonyl group. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes.
In organic chemistry, a dicarboxylic acid is an organic compound containing two carboxyl groups. The general molecular formula for dicarboxylic acids can be written as HO2C−R−CO2H, where R can be aliphatic or aromatic. In general, dicarboxylic acids show similar chemical behavior and reactivity to monocarboxylic acids.
Enanthic acid, also called heptanoic acid, is an organic compound composed of a seven-carbon chain terminating in a carboxylic acid functional group. It is a colorless oily liquid with an unpleasant, rancid odor. It contributes to the odor of some rancid oils. It is slightly soluble in water, but very soluble in ethanol and ether. Salts and esters of enanthic acid are called enanthates or heptanoates.
Pelargonic acid, also called nonanoic acid, is an organic compound with structural formula CH3(CH2)7CO2H. It is a nine-carbon fatty acid. Nonanoic acid is a colorless oily liquid with an unpleasant, rancid odor. It is nearly insoluble in water, but very soluble in organic solvents. The esters and salts of pelargonic acid are called pelargonates or nonanoates.
Omega oxidation (ω-oxidation) is a process of fatty acid metabolism in some species of animals. It is an alternative pathway to beta oxidation that, instead of involving the β carbon, involves the oxidation of the ω carbon. The process is normally a minor catabolic pathway for medium-chain fatty acids, but becomes more important when β oxidation is defective.
Lipid metabolism is the synthesis and degradation of lipids in cells, involving the breakdown and storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes. In animals, these fats are obtained from food and are synthesized by the liver. Lipogenesis is the process of synthesizing these fats. The majority of lipids found in the human body from ingesting food are triglycerides and cholesterol. Other types of lipids found in the body are fatty acids and membrane lipids. Lipid metabolism is often considered as the digestion and absorption process of dietary fat; however, there are two sources of fats that organisms can use to obtain energy: from consumed dietary fats and from stored fat. Vertebrates use both sources of fat to produce energy for organs such as the heart to function. Since lipids are hydrophobic molecules, they need to be solubilized before their metabolism can begin. Lipid metabolism often begins with hydrolysis, which occurs with the help of various enzymes in the digestive system. Lipid metabolism also occurs in plants, though the processes differ in some ways when compared to animals. The second step after the hydrolysis is the absorption of the fatty acids into the epithelial cells of the intestinal wall. In the epithelial cells, fatty acids are packaged and transported to the rest of the body.
In biochemistry, fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases. This process takes place in the cytoplasm of the cell. Most of the acetyl-CoA which is converted into fatty acids is derived from carbohydrates via the glycolytic pathway. The glycolytic pathway also provides the glycerol with which three fatty acids can combine to form triglycerides, the final product of the lipogenic process. When only two fatty acids combine with glycerol and the third alcohol group is phosphorylated with a group such as phosphatidylcholine, a phospholipid is formed. Phospholipids form the bulk of the lipid bilayers that make up cell membranes and surrounds the organelles within the cells.
In organic chemistry, a homologation reaction, also known as homologization, is any chemical reaction that converts the reactant into the next member of the homologous series. A homologous series is a group of compounds that differ by a constant unit, generally a methylene group. The reactants undergo a homologation when the number of a repeated structural unit in the molecules is increased. The most common homologation reactions increase the number of methylene units in saturated chain within the molecule. For example, the reaction of aldehydes or ketones with diazomethane or methoxymethylenetriphenylphosphine to give the next homologue in the series.
Pentadecylic acid, also known as pentadecanoic acid or C15:0 is an odd-chain saturated fatty acid. It is a colorless solid.
Cerotic acid, or hexacosanoic acid, is a 26-carbon long-chain saturated fatty acid with the chemical formula CH3(CH2)24COOH. It is most commonly found in beeswax and carnauba wax. It is a white solid, although impure samples appear yellowish.
Tridecylic acid, or tridecanoic acid, is the organic compound with the formula CH3(CH2)11CO2H. It is a 13-carbon saturated fatty acid. It is a white solid.
Heneicosylic acid, or heneicosanoic acid, is the organic compound with the formula CH3(CH2)19CO2H. It is the straight-chain 21-carbon saturated fatty acid. It is a colorless solid.
Paraffin oxidation is a historical industrial process for the production of synthetic fatty acids. The fatty acids are further processed to consumer products such as soaps and fats as well as to lubricating greases for technical applications. Coal slack wax, a saturated, high molecular weight hydrocarbon mixture and by-product of the Fischer–Tropsch process was used as raw material. Side products were a wide range of carboxylic acids and oxidation products such as alcohols, aldehydes, esters, or ketones. The oxidation of paraffins was carried out in the liquid phase by molecular oxygen, e.g. by aerating with oxygen or atmospheric air, in the presence of catalysts such as permanganates, e.g. 0.1% - 0.3% potassium permanganate, at temperatures in the range of about 100 to 120 °C and under atmospheric pressure.
